Dr. Bennet Omalu, a forensic pathologist and leading expert in the field of concussion research, wrote an op-ed piece Monday for the New York Times in which he argued that parents shouldn't have their children play football and other high-impact contact sports before the age of 18.

"Our children are minors who have not reached the age of consent," Dr. Omalu wrote. "It is our moral duty as a society to protect the most vulnerable to us."

According to Dr. Omalu—whose research and fight with the NFL is the focus of Concussion, the film starring Will Smith that opens Christmas Day—the human brain becomes fully developed at about 18 to 25 years old. "We should at least wait for our children to grow up, be provided with information and education on the risk of play, and let them make their own decisions," he wrote. "No adult, not a parent or a coach, should be allowed to make this potentially life-altering decision for a child."

Repeated blows to the head can contribute to permanent brain damage, or chronic traumatic encephalopathy, commonly known as CTE, which Dr. Omalu said causes depression, memory loss, suicidal thoughts, and loss of intelligence later in life.

The worst part, however, is that the damage is irrepairable. "The risk of permanent impairment is heightened by the fact that the brain, unlike most other organs, does not have the capacity to cure itself following all types of injuries," Dr. Omalu wrote. "We are born with a certain number of neurons. We can only lose them; we cannot create new neurons to replenish old or dying ones."

Dr. Omalu pointed to age restrictions for other harmful activities such as smoking and drinking while making his case for placing restrcitions on football. "As physicians, it is our role to educate and inform an adult about the dangers of, for example, smoking," he wrote. "We have a legal age for drinking alcohol; for joining the military; for voting; for smoking; for driving; and for consenting to have sex. We must have the same when it comes to protecting the organ that defines who we are as human beings. The question we have to answer is, when we knowingly and willfully allow a child to play high-impact contact sports, are we endangering that child?"